In LTE (Long Term Evolution), a handover control is specified in order that a mobile station UE can perform communications in an optimal cell even when the mobile station UE moves (see FIG. 6).
Moreover, CA (Carrier Aggregation) specified until LTE Release-10 is able to achieve the high throughput by performing simultaneous communication using a CC (Component Carrier) #1 and a CC#2 under the same radio base station eNB, as illustrated in FIG. 7(a).
Meanwhile, in LTE Release-12, discussed is “Inter-node UP aggregation” to which the CA until LTE Release-10 is further extended. The “Inter-node UP aggregation” achieves high throughput by performing simultaneous communication using a CC#1 and a CC#2 respectively under different radio base stations eNB#1 and eNB#2, as illustrated in FIG. 7(b) (see Non-patent document 1).
For example, if all the CCs cannot be accommodated in a single radio base station eNB, it is necessary to perform the “Inter-node UP aggregation” in order to achieve the throughput comparable to that of LTE Release-10.
Further, in the “Inter-node UP aggregation”, an anchoring node is expected to distribute downlink data to transmit the downlink data to a mobile station UE.
For example, a radio base station MeNB that manages a macro cell is an anchoring node in an example of FIG. 8(a) and a gateway device S-GW is an anchoring node in an example of FIG. 8(b).